External Gap between skylight windows and wall

[svenz]

https://imgur.com/a/5LhYS5y

I have this 20 yo side extension with skylight windows attached to guttering. There is a 10mm gap from exterior to interior under the overhang. Currently foam wedges have been stuck there to stop draughts.

What would be the best way to properly seal this gap up? thanks.

 

[robinbanks]

Is the area under the roof windows a heated or unheated space?

 

[svenz]

Is the area under the roof windows a heated or unheated space?

Heated space - goes directly into the side extension interior.

 

[robinbanks]

Are the roof windows double glazed? I see only a single pane in the picture but it's possible to have DG units manufactured with a single glazed overhang

 

[svenz]

Are the roof windows double glazed? I see only a single pane in the picture but it's possible to have DG units manufactured with a single glazed overhang

They are double glazed. Could I buy some kind of upvc trim and use mastic to seal it up?

 

[robinbanks]

Sure. Remember to insulate it